Would appreciate if u could provide explanation to solve this q. Thanks.

Leela and Kumar shared a sum of money.
Leela's share was $90 less than Kumar's.
After Kumar gave 1/7 of his share to Leela,Leela had $10 more than Kumar.
a) how much did Leela have at first? (Ans: $260)
b) what was the sum of money. (Ans: $610)

<Before>
Apply <work backward> method, K would have that 1 part {K did not give 1/7 of his share to L} while L would not have that 1 part. Given that L's share was $90 less than K, the model becomes ...